Hybrid-type synchronous machine

Abstract

A rotor core has permanent magnets. Magnetic flux of the permanent magnet of an even-numbered rotor magnetic pole part is guided in an axial direction by an axial magnetic path member. Magnetic flux of the permanent magnet of an odd-numbered rotor magnetic pole part is guided into a soft magnetic inner cylindrical part. The axial end faces of the inner cylindrical part and the axial magnetic path member protrude from the rotor core in the axial direction and face a stationary magnetic path member with a small gap therebetween. The amount of magnetic flux of the magnet, which the permanent magnet applies to a stator core is adjusted by an excitation current of an excitation coil wound on the stationary magnetic path member.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on and incorporates herein by reference Japanese Patent Application No. 2008-144712 filed on Jun. 2, 2008.FIELD OF THE INVENTION[0002]The present invention relates to a hybrid excitation-type synchronous machine, which includes a field coil and permanent magnets to generate field magnetic flux of a rotor.BACKGROUND OF THE INVENTION[0003]A synchronous machine includes a field coil-type synchronous machine, a permanent magnet-type synchronous machine and a reluctance motor. In the field coil-type synchronous machine, field magnetic flux of a rotor is generated by an excitation coil (field coil). In the permanent magnet-type synchronous machine, magnet flux generated by permanent magnets is used as filed magnetic flux. In the reluctance motor, reluctance torque is generated by magnetic resistance variation of a salient pole-type rotor core, which rotates relative to a salient pole-type stator core.[0004]The permanent...

AI Technical Summary

Benefits of technology

[0008]It is an object of the present invention to provide a hybrid excitation-type synchronous machine, which is simple in magnetic path configuration and improves a parallel-type hybrid excitation system.

[0012]As a result, a series hybrid excitation-type synchronous machine can be formed, and hence the following advantages can be provided.

[0013]Since the excitation coil and the permanent magnet are arranged in series in the flux path of the field magnetic flux, the field magnetic flux can be increased without energizing the excitation coil in a mode that magnetism is not increased or decreased. That is, since loss of excitation current is not caused in an operation mode, in which the magnet magnetic flux is used to the maximum extent, the decrease in efficiency caused thereby can be minimized. For example, in an electric motor for a vehicle, the rotation speed of the rotor is not so large in most of its operation period, and no magnetization decreasing control is necessitated. Therefore, the magnetization loss is eliminated in most part of the operation period.

[0014]Further, the magnetic path of the field magnetic flux is formed by arranging the stationary magnetic path members in proximity to the end surfaces of the rotor core. Here, the stationary magnetic path member is interposed between the inner cylindrical part and the even-numbered rotor magnetic pole part, which is spatially (magnetically) separated from the inner cylindrical part used as the back yoke of the rotor core. Thus, the length of the magnetic path can be shortened. As a result, the weight of soft magnetic material having a large specific gravity can be reduced and hence the motor can be reduced in weight.

Problems solved by technology

However, if the d-axis current is reduced, loss due to the d-axis current is large.

As a result, the amount of magnetic flux of the magnet that crosses the stator coil decreases and hence torque decreases.

As a result, excitation loss increases.

Thus, the weight of the motor increases, and a part of the magnetic flux of the excitation coil is likely to leak to a bearing section.

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